Radar device, signal processor, and signal processing method

Abstract

To provide a radar device capable of improving azimuth estimation accuracy by compensating the Doppler phase shift of a moving target in a TDMA FMCW MIMO radar device. Provided is a radar device that allows transmitting antennas to perform transmission by performing sequential switching such that antenna element numbers are anterior-posterior symmetrical centering on a reference time and synthesizes a beat signal at the reference time from a first beat signal received by a receiving antenna before the reference time and a second beat signal received after the reference time.

What is claimed is: 
     
       1. A radar device comprising:
 M (M≥2) number of transmitting antennas; 
 N (N≥1) number of receiving antennas; 
 a local oscillator configured to oscillate a local signal; 
 a transmission processing unit configured to transmit a transmission signal based on the local signal by selecting any one of the transmitting antennas; 
 a reception processing unit configured to output a beat signal from an echo signal obtained from the transmission signal reflected by a target and the local signal, the echo signal being received by the receiving antennas; and 
 a signal processing unit configured to perform signal processing on the beat signal, 
 the transmission processing unit causes the transmitting antennas to perform transmission by performing sequential switching such that transmission antenna transmission times are anterior-posterior symmetrical centered around a reference time, and 
 the signal processing unit synthesizes a beat synthesized signal at the reference time from a first beat signal received by the receiving antenna before the reference time and a second beat signal received after the reference time. 
 
     
     
       2. The radar device according to  claim 1 ,
 wherein the signal processing unit obtains an amplitude of the synthesized beat signal at the reference time by averaging an amplitude of the first beat signal and an amplitude of the second beat signal and obtains a phase of the synthesized beat signal at the reference time by adding a phase of the first beat signal and a phase of the second beat signal. 
 
     
     
       3. The radar device according to  claim 1 ,
 wherein the signal processing unit synthesizes a frequency spectrum of the synthesized beat signal at the reference time from a first frequency spectrum obtained by performing discrete Fourier transform on the first beat signal and a second frequency spectrum obtained by performing the discrete Fourier transform on the second beat signal. 
 
     
     
       4. The radar device according to  claim 1 ,
 wherein the signal processing unit, if an average of an amplitude of the first beat signal and an amplitude of the second beat signal is equal to or less than a predetermined value, sets the first beat signal or the second beat signal as the synthesized beat signal at the reference time. 
 
     
     
       5. The radar device according to  claim 4 ,
 wherein the predetermined value is a predetermined ratio of the amplitude of the first beat signal or the amplitude of the second beat signal. 
 
     
     
       6. The radar device according to  claim 1 ,
 wherein the radar device is mounted on a vehicle. 
 
     
     
       7. A signal processor comprising:
 a signal processing unit configured to perform signal processing on a beat signal generated from an echo signal obtained from a transmission signal that is transmitted from M (M≥2) number of transmitting antennas and reflected by a target and a local signal, the transmission signal being based on the local signal, 
 wherein the signal processing unit causes the transmitting antennas to perform transmission by performing sequential switching such that transmission antennas transmission times are anterior-posterior symmetrical centered around a reference time, and 
 synthesizes a beat synthesized signal at the reference time from a first beat signal received by the receiving antenna before the reference time and a second beat signal received after the reference time. 
 
     
     
       8. A signal processing method comprising:
 causing M (M>2) number of transmitting antennas to transmit a transmission signal based on a local signal by performing sequential switching such that transmitting antennas transmission times are anterior-posterior symmetrical centered around a reference time; and 
 performing signal processing on a beat signal generated from an echo signal obtained from the transmission signal that is transmitted from the transmitting antennas and reflected by a target and the local signal, 
 wherein the performing of the signal processing includes synthesizing a synthesized beat signal at the reference time from a first beat signal received by the receiving antenna before the reference time and a second beat signal received after the reference time.